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<head>
    <meta charset="UTF-8">
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    <title>Document</title>
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    <style>
        * {
            margin: 0px;
            padding: 0px;
            font-size: 12px;
        }

        a {
            color: #999;
            text-decoration: none;
        }

        body {
            background: #fff url(../images/bg.jpg) no-repeat;
        }

        ul {
            list-style: none;
        }

        .pos {
            position: absolute;
        }

        #menu {
            left: 590px;
            top: 5px;
        }

        #menu li {
            display: block;
            height: 20px;
            line-height: 20px;
            background-color: #fff;
            padding: 4px;
        }
    </style>
</head>

<body>
    <div id="menu" class="pos">
        <a href="#">我的当当</a>
        <ul id="menu-ul" style="display:none;">
            <li><a href="#">我的订单</a></li>
            <li><a href="#">我的收藏</a></li>
            <li><a href="#">我的礼品卡</a></li>
            <li><a href="#">我的积分</a></li>
            <li><a href="#">我的余额</a></li>
        </ul>
    </div>
    <script>
        $('div').mouseover(function(){
            $('#menu-ul').show()
        })
        $('div').mouseout(function(){
            $('#menu-ul').hide()
        })

    </script>
</body>

</html>